1. Field of the Invention
The present invention relates to a magnetic storage element preferably applicable to a non-volatile memory, a recording method using the same, and a magnetic storage device using the magnetic storage element.
2. Description of Related Art
In information apparatuses such as computers, a DRAM which is operable at a high speed and having a large storage density is widely used as random access memories therefor. The DRAM is however classified as a volatile memory which cannot keep information when the power supply is interrupted, so that there is a demand for non-volatile memory which can keep information at any time.
One example of the non-volatile memory relates to a magnetic random access memory (MRAM) which uses magnetic storage elements capable of recording information based on a magnetization state of a magnetic material (see non-patent document 1, for example).
[Non-Patent Document 1]
Nikkei Electronics, Feb. 12, 2001 (p.164–171)
The above-described MRAM is configured as a magnetic storage device in which two kinds of wirings (a word line and a bit line, for example) crossing normal to each other are individually formed plural in number, and a magnetic storage element is provided at every intersection of these two wirings, so that a large number of magnetic storage elements are arranged according to a matrix pattern. Information is recordable by electrifying a specific line respectively selected from these two kinds of wirings to thereby select a magnetic storage element located at the intersection of both activated lines, and by inverting the magnetization of a storage layer of the selected magnetic storage element by a current-induced magnetic field.
Any variations in the magnetic characteristics of the individual magnetic storage elements composing the MRAM may however cause magnetization inversion also in magnetic storage elements other than targeted ones (those to be recorded), and this undesirably prevents correct recording. On the contrary, weakening of the current-induced magnetic field to a sufficiently low level aiming at completely prevent the magnetic storage elements other than the targeted ones from causing the magnetization inversion may fail in recording for a part of the targeted magnetic storage elements.
Because trends for the future require the MRAM to further raise density for a larger storage capacity, and to reduce size of the magnetic storage element composing memory cells thereof, it is also necessary to reduce size of the magnetic material used for the storage layer of the magnetic storage element.
The magnetic material, however, tends to increase its coercive force as the size thereof is reduced, and this inevitably raises a coercive force of the storage layer also in the magnetic storage elements of the MRAM with progress of the size reduction. This type of increase in the coercive force makes it difficult to reduce variations in the coercive force of the individual magnetic storage elements.